Makefile no longer needs passwd, pwd.db and spwd.db due to fixed pwd_mkdb

Makefile no longer needs passwd, pwd.db and spwd.db due to fixed pwd_mkdb
that now takes a directory argument.  These files are now built from the
master.passwd file.

Fixed typo on NOOBJ=, was oobj, now noobj.
Rename of targes and variables.  INST1 -> FILESYSTEM, INST2 -> CPIO,
kc -> kcopy.

Floppy targets now dd and gzip the image back onto the hard disk so
that less manual work is required when building a release.

Removed reboot from FILESYSTEM floppy and put df back on, and added
mount_isofs.  Changed scripts to use halt instead of reboot.